1. Field of the Invention
The invention relates to a microphone package, and more particularly to a microphone package with a minimum footprint size and thickness.
2. Description of the Related Art
Electronic devices are becoming increasingly compact and lightweight. Many electronic devices have microphones inside. Therefore, modifying the structure of a microphone to have a minimum size is required.
U.S. Pat. No. 6,781,231 discloses a microelectromechanical system package with an environmental and interference shield. As shown in FIG. 1, a cover 20 is disposed on a substrate 23. The cover 20 serving as an environmental and interference shield includes an outer cup 25a and an inner cup 25b. A plurality of electronic elements 12 is disposed in a chamber 36 formed by the cover 20 and the substrate 23. The cover 20 has a plurality of acoustic ports 44 and 48 allowing the electronic elements 12 to receive external sound.
The electronic elements 12 are arranged side-by-side, thus having a large footprint size on the substrate 23. The size of the microelectromechanical system package thus, can not meet modern electronic device requirements for extreme compactness.
U.S. Patent Application Publication No. 2007/0278601 discloses a MEMS (micro-electro-mechanical system) device. As shown in FIG. 2, a MEMS die 110 is mounted on a chip carrier 120 and encapsulated by an enclosure 130. The chip carrier 120 has an acoustic hole 125 covered by the MEMS die 110. The enclosure 130 is used for preventing transmission of any electromagnetic radiation from the MEMS die 110, and any electromagnetic radiation from interfering with the MEMS die 110. The enclosure 130 may be molded using a thermoplastic or thermosetting polymer material, such as epoxy molding compound, liquid crystal polymer, or polyetheretherketone (PEEK), and an electrically conductive material, such as metal particles or carbon fibers or fillers.
The MEMS die 110 with a microphone and an integrated circuit combined therein has a minimum size. However, the technique of combining the microphone and the integrated circuit in a MEMS die is not yet matured. Thus, the reliability of the MEMS die is not appropriately applicable.
U.S. Pat. No. 6,522,762 discloses a silicon-based sensor system. As shown in FIG. 3, a transducer 1 and an integrated circuit chip 3 are flip-chip mounted on a silicon carrier substrate 2. The transducer 1 and the integrated circuit chip 3 are electrically connected. The second surface of the silicon carrier substrate 2 is supplied with a plurality of solder bumps 22 for surface mounting onto a printed circuit board (not shown). A lid 5 provides EMI (electromagnetic interference) shielding. An EMI shield 16 is a conductive polymer layer such as silver epoxy, or a metal layer such as electroplated or evaporated Cu or Au.
Similarly, the transducer 1 and integrated circuit chip 3 are arranged side-by-side, thus having a large footprint size on the silicon carrier substrate 2. The size of the silicon-based sensor system thus cannot meet modern electronic device requirements for extreme compactness.
U.S. Pat. No. 7,202,552 discloses a MEMS package using flexible substrates. As shown in FIG. 4, the MEMS package 70 has a MEMS device 40 attached to the flexible substrate 10. A metal cap 54 encapsulates the MEMS device 40 on the flexible substrate 10. The flexible substrate 10 is folded over the metal cap 54 and glued to the top of the metal cap 54. The metal cap 54 and the metal layer of the flexible substrate 10 are electrically connected to form a Faraday cage for EMI/RF shielding.
Similarly, all the devices are arranged side-by-side, thus having a large footprint size on the flexible substrate 10. The size of the MEMS package thus cannot meet modern electronic device requirements for extreme compactness.